From: Francesco Cerutti (Francesco.Cerutti@cern.ch)
Date: Mon Jan 29 2007 - 21:10:31 CET
Dear Hamide,
> First,in the case of ENELOW and ENEUP values' in source.f, They are in
> term of Gev/n, Should I convert them to Gev,then FLUKA itself consider them
> in term of Gev/n for heavy ion?
TKEFLK (NPFLKA) is the TOTAL kinetic energy of your nucleus expressed in
GeV. So if you load values in GeV/n, you have to multiply your ENERGY
variable by dble(IPROA) (i.e. 12) before assigning its value to
TKEFLK(NPFLKA).
> Second,you had mentioned that I must define an isotropic property of my
> source in my own source.f .I had done it before but I omitted it according
> to Fasso's recommendation.If I eliminate the commands of Cos(tx,ty,tz) from
> my source.f is it correct to consider this character with BEAM?
> I had given these commands in source.f to define an isotopic source.
>
> * Isotropic angular distribution
> YI = FLRNDM(DUMMY)
> COSTH = ONEONE - 2.D0 * YI
> IF (COSTH .GT. ONEONE) THEN
> COSTH = ONEONE
> ELSE IF (COSTH .LT. -ONEONE) THEN
> COSTH = -ONEONE
> END IF
> ZI = FLRNDM(DUMMY)
> ANG = TWOPIP * ZI
> UBEAM = SQRT (ONEONE - COSTH * COSTH) * COS(ANG)
> VBEAM = SQRT (ONEONE - COSTH * COSTH) * SIN(ANG)
> WBEAM = COSTH
If you want an isotropic distribution, you do not need a customized source
routine (the point - right - of Alberto). But if you need your own source
routine for other reasons (sampling from a special spectrum), then you
have to define there the direction cosines too. Your above coding seems to
be correct.
Remember that you have to define U[vw]BEAM BEFORE assigning
their values to TX[yz]FLK (NPFLKA). The same holds for X[yz]BEAM with
respect to X[yz]FLK (NPFLKA).
Florian was just hinting at this point:
> **In your source.f you set the beam position for the first particle to the
> defaults i.e. (0.,0.,0.) and for the remaining particles to
> XBEAM = 4.D05
> YBEAM = 4.D05
> ZBEAM = 4.D05
This is because you write
XFLK (NPFLKA) = XBEAM
YFLK (NPFLKA) = YBEAM
ZFLK (NPFLKA) = ZBEAM
XBEAM = 4.D05
YBEAM = 4.D05
ZBEAM = 4.D05
instead of
XBEAM = 4.D05
YBEAM = 4.D05
ZBEAM = 4.D05
XFLK (NPFLKA) = XBEAM
YFLK (NPFLKA) = YBEAM
ZFLK (NPFLKA) = ZBEAM
The first particle starts at the center of your Al shell, the following
ones almost 7km far away.
> Then you set the direction cosines to:
>
> (UBEAM, VBEAM, WBEAM)= (0., 0. , 1.)
This is because you do not define the direction cosines (default values
are taken).
> With this settings you may hit the volume defined by your USRBIN with
> the first particle but never with the others and therefor the output
> contains only zeros.**
The effect is that only the first particle goes through your Al shell, the
others never see it.
But please note that placing an isotropic source 7km far away from a 20m
diameter sphere means that the probability that one nucleus impinges on it
is VERY small since the solid angle covered by your shell is less than
10 usr (i.e. 10^-5 sr, to be compared with 4*pi sr!). Thus you have to
sample much more efficiently the carbon directions (you are interested
just in the ions hitting the Al shell).
Finally your USRBIN R-PHI-Z binning looks strange: you are scoring over a
cylinder at z~5.5m and R~10m, i.e. OUTSIDE the Al shell (at z~5.5m your Al
shell has a distance R from the z axis of about 8m) where you have vacuum
and so you will get always zero energy deposition.
Ciao!
Francesco
**************************************************
Francesco Cerutti
CERN-AB
CH-1211 Geneva 23
Switzerland
tel. ++41 22 7678962
fax ++41 22 7668854
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